The present invention relates to a mount insulator to be used for elastically supporting a shock absorber of a suspension at the car body side.
This type of mount insulator has so far been provided between the upper section of the shock absorber and the car body side. The shock absorber is structured by a rod section and a cylinder section. A rear spring bumper is provided to surround the shock absorber, and a first retainer, the shock absorber and a second retainer are provided in a stacked state at the upper section of the rear spring bumper. The rod section passes through the first retainer, the shock absorber and the second retainer, and at the upper portion of the second retainer, and a nut is fastened to a male screw section formed at the front end of the rod section. By the fastening of this nut, a mount insulator is mounted between the first retainer and the second retainer. A coiled spring is provided outside the shock absorber. The upper and lower positions of the coiled spring are restricted by coiled spring receiver provided at a cylinder section of the shock absorber and by the mount insulator.
The mount insulator is structured by a core metal body fixed to a strut housing at the car body side, a rubber elastic section having a piercing hole (viz., through hole), and an inner cylinder section mounted in the piercing hole of the elastic body section and having the rod section pierced (viz. disposed) through a bore section of the inner cylinder section.
The core metal body is formed in approximately a disk shape, and a hole section having a larger diameter than the outer diameter of the inner cylinder is provided at approximately the center portion of the core metal body. A rising section projecting upwards is provided at the periphery of the hole section. The outer periphery side of the core metal body structures a spring sheet section.
A mount elastic body section of the elastic body section is fixedly formed on both the upper and lower surfaces of the core metal body, on an inner periphery surface of the hole section and the rising section, and on the outer periphery surface of the inner cylinder section respectively. A spring receiving elastic body is fixedly formed on the lower surface of the spring sheet section. The spring receiving elastic body is integrated with the mount elastic body to structure the elastic body section. The mount elastic body section is expansively formed in the axial direction of the inner cylinder section, and the upper and lower ends of the inner cylinder and the mount elastic body section are on almost the same plane.
The mount insulator is mounted in the state that the rod section is inserted in the inner cylinder section and that the inner cylinder section and the mount elastic body section are sandwiched between the first and second retainers. In the spring sheet section, the coiled spring is received by the spring receiving elastic body section. Accordingly, both the shock absorber and the coiled spring are elastically supported by the strut housing at the car body side.
However, since the core metal body is formed in almost a disk shape in the above-described type of mount insulator, the mount elastic body section is easily deformed to escape in the lateral direction. Therefore, when a force is applied in a direction perpendicular to the axis of the rod section due to the entangled stiffness of a lower bush of the shock absorber, the rod section and the inner cylinder section are inclined to the lateral direction with respect to the core metal body fixed to the strut housing. Accordingly, since the mount elastic body section is strongly compressed between the rising section of the core metal body and the inner cylinder section, there is a problem that the mount elastic body section is easily damaged. Particularly, since the rising section becomes an edge, the mount elastic body section is easily damaged.
Further, since the mount insulator integrally holds the inner cylinder section and is sandwiched by the retainers on both sides, it is not possible to apply a preliminary pressure to the mount elastic body section even if the nut is fastened. Accordingly, there arises a problem that the retainers and the upper and lower ends of the mount elastic body section are brought into contact with each other or are separated from each other when a damping force of the shock absorber is applied or when a force is applied in upward and downward directions by the rear spring bumper. This further leads to such problems that abnormal noise is generated and that the mount elastic body section is damaged by sands that enter in the gap between the retainers and the upper and lower ends of the mount elastic body section.